Animals In Print
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From 26 March 2002
Hunting Is Not The Cure But The Cause Of Overpopulation And Starvation
From Peter Muller
To see exactly how hunting is destructive to an ecosystem, let’s look at a specific game animal. Probably the most widely hunted animal in North America is one of the common species of deer (white-tailed, mule deer, or black-tailed with an aggregate of about 50 subspecies)
Let’s consider a naturally segmented area has sufficient browse to feed a deer herd of 400 animals. Wildlife biologists would describe this by saying that the biological carrying capacity of the area for deer is 400. A territory has associated with it a carrying capacity for each species that has naturally evolved there. Nature has mechanisms in place to ensure that the carrying capacity that is appropriate for that species is not exceeded. What would happen if the deer population increased to substantially over 400 in one year?
Let’s say that with all normal control mechanisms in place (including natural predators) the herd size reaches 500 healthy individuals. At the start of the next rut, several mechanisms would kick in to ensure a smaller amount of fawns the following year. If deer are hungry (not starving, but not well fed either), the sex drive of the bucks declines and the does stop ovulating or become receptive less frequently than they would if plenty of browse is available. Since the browse is now insufficient to feed all 500 animals, a portion of the deer population would not reproduce during that season. With the normal die-off during the winter and the smaller than normal birth during the spring, the total population would be reduced to less that 500.
Within a few seasons the populations would again stabilize around the capacity of the territory. If the herd size dropped substantially below the carrying capacity (say to 300), other natural mechanisms would kick in (for example, does who have lots of browse during the rut are more likely to have twins or triplets) to bring the population back up to the normal carrying capacity of 400. Many other mechanisms, some simple and some fairly involved and not yet completely understood, are used by nature to maintain the population at the carrying capacity.
These mechanisms with which the species have evolved have, built into them, assumptions that have been true for millions of years. Human hunting totally destroys some of these assumptions
Normally, left to their own devices, the sex ratio of male to female animals is about 50-50. Deer are born about evenly male and female. Most “sport” or “trophy” hunters prefer to take bucks rather than does. Almost state game agencies mandate that during the regular hunting only bucks (antlered deer) and no does are shot. Under certain extreme conditions, where a deer population has totally mismanaged for years “doe permits” are issued in addition to the regular deer tags in a desperate attempt to mitigate the mess that the agencies have created over the years. This policy of shooting out bucks distorts the gender ratio of the population.
Let see what happens when that ratio changes from 50-50 ratio to 80-20 –leaving four times as many does as bucks This is not at all uncommon. In Texas and the Southwest, in general, years of mismanagement have pushed the doe to buck ratio as high as 10:1 in some areas.
Let’s look at two herds – one unhunted with the gender ratio intact at 50/50 and one hunted and one hunted with the gender ration skewed to 80/20. Otherwise everything is the same both herds live in an area where there is sufficient browse for 400 animals. Nature’s mechanisms that adjust the population to the browse will now miscalculate and cause an overpopulation for the hunted herd but leave the unhunted herd stable at 400 animals.
Based on 50-50 ratio, a herd of 400 will consist of 200 bucks and 200 does. Normal browse conditions signal to each doe to give birth to a single fawn. Assuming a winter die-off of 100 deer. The surviving herd would consist of 150-buck and 150 does. Each of the 150 does would give birth to 150 fawns. The herd sized, including the new 150 fawns is now 450. Fawns have about a 2/3 chance of surviving until the next fall because they are subject to more predation than adult deer; for example, coyotes will predate on fawns but rarely on fully grown deer. Other mortality rates are also higher for fawns that adult deer. At the next rut the herd is back to 400.
Based on an 80/20 gender ratio, a 100 animal winter die-off, and normal browse conditions there will 240 does and 60 bucks in the surviving herd. The 240 does will give birth to 240 fawns of which 160 will survive. At the next rut the herd size is now 460 instead of 400. That’s a 15% increase over the normal her size. A few successive seasons like that and the herd approaches conditions where massive, catastrophic starvation and die-offs are inevitable.
Hunting is not the cure but the cause of overpopulation and starvation. Luke Dommer, the founder of the Committee to Abolish Sport Hunting, has proposed to several times to various state wildlife agencies that if they are serious about using hunting as a population control tool in areas where the sex ratio is already badly distorted, they should institute a doe-only season. (Taking no bucks but only does until the ratio is again stabilized at 50:50). All agencies have rejected that proposal – thereby giving up any pretense of ecologically motivated sound wildlife management. They quite consciously and openly state that they are in business to provide the maximum number of live targets to hunters each year.
The state agencies encourage the destruction of the naturally evolved ecosystem by encouraging human hunting that balloons the population of the game species at the expense of the non-game species. Management techniques, in addition to sex-ratio distortion, include removal of natural predators (e.g. wolves, coyotes, panthers, bears) altering the natural habitat to provide additional browse for game species and destroying the habitat of non-game species (e.g. clear-cutting and/or burning areas and sowing them with oats for deer at the expense of rabbits, voles, various reptiles and amphibians – and many other non-games species.)
Things sometimes go totally haywire if a species is introduced into an ecosystem where it didn’t evolve. Biologists call such an organism an “exotic” animal or plant. If the exotic animal is a prey species, it may have no defenses against a local predator and be totally wiped out in a very short time. On the other hand, it may not have any local predators and consequently proliferate beyond the carrying capacity of the territory, causing catastrophic die-off through starvation.
If an exotic predator is introduced, the exotic species itself may die out if there is no suitable local prey. Or, it may cause the extinction of local prey species who have no defenses against the exotic predator. Or, it may cause the extinction of local predators if it is more successful and out-competes the local predator species in taking the prey.
Numerous examples of the consequence of introduction of exotic organisms within environments where they have not evolved can be cited: The introduction of snakes into Guam during World War II to control the rat population nearly wiped out several indigenous bird species; introducing trout for sport fishing into Lake Titicaca in Peru in the 1930s wiped out about 25 species of local fish. Those fish were not found anywhere else in the world. There are hundreds of examples where the introduction of an exotic species had a deleterious effect on an ecosystem.
The wildlife management agencies defy sound procedure by such practices as introducing exotic game species into areas and then distorting the habitat to favor their survival at the expense of native species that have evolved in the area. e.g. stocking an area with pheasants –an Asian bird—and cutting tall timber trees needed by native raptors for perches.
The activity of human hunting is not and never has been a sustainable, mutually beneficial, predator, prey relationship. Human hunting techniques, even the most primitive ones, are far too efficient to meet the conditions required of a natural predator-prey relationship. In modern times, with new technology, the efficiency becomes totally lopsided so as to cause instant habitat degeneration. Add to this the conscious mismanagement of habitat to further degrade and obviate all natural corrective measures.
Using techniques such as sex-ratio distortion, habitat manipulation, the removal of natural predators and the introduction of exotic game species destroys biodiversity. The goal is to maximize the number of targets for human hunting, thereby destroying the naturally evolved ecosystems and putting them at the brink of total collapse.
The number of animals of game species (native and exotic) is maximized at the expense of all others. The naturally evolved mechanisms that insure biodiversity are short-circuited.
The only way that these ecosystems can recover is to prohibit human hunting and all other forms of non-sustainable consumptive uses of these animals. We should allow for the unfettered reintroduction and re-immigration of predators (which is occurring naturally). Stop “managing” the environment of those areas. When it comes to managing the environment, our knowledge is inadequate to do an even passable job. Even given an ethically sound motivation, which the state agencies now lack, we simply don’t know enough to do a better job than nature.
Rather than playing God, we ‘re acting more like the three stooges, when it comes to managing ecosystems. For the sake of life on earth, we must not allow the hunting and gun-manufacturing lobbies to continue to dictate wildlife management policies.
For more info: http://all-creatures.org/cash/
Committee to Abolish Sport Hunting
Wildwatch.org Email: [email protected]
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